1. Field of the Invention
This invention relates to increasing the maneuverability of apparatus for milling or cutting grooves in road surfaces and particularly to improving the ability to steer such apparatus so as to enable the paved surface being worked to be cut in close proximity to obstructions such as manhole covers. More specifically, the present invention is directed to an improved steering mechanism for a road cutter or the like and especially to a steering mechanism which permits such highway maintenance apparatus to be turned through a substantially greater steering angle than has previously been possible. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
Highway grooving or milling machines are well known in the art. An exemplary machine for milling road surfaces is shown in Canadian Patent No. 994,145. The typical prior art road cutter is provided with a pair of forwardly mounted guide wheels. These guide wheels are customarily provided with independent hydraulic drives which may, for example, include hub mounted gearing. In order to steer a road cutter, the guide wheels are supported so as to be rotatable relative to the chassis of the apparatus. The prior art guide wheel steering mechanism includes a steering knuckle associated with each wheel. The guide wheels of the typical prior art road cutter are supported from a rocker arm and the steering knuckles are interconnected by means of a track rod. A fluidic actuator is connected between the rocker arm and one of the steering knuckles. The angular orientation of the guide wheels relative to the chassis of the apparatus may thus be changed to a newly desired steering angle by energizing the fluidic actuator. This arrangement, in effect, is a parallelogram-type linkage which inherently provides a relatively small maximum steering angle. Under certain operating conditions the maximum obtainable steering angle which may be achieved through use of such a parallelogram linkage does not afford adequate maneuverability. For example, when a prior art steering mechanism of the type described is employed, it has been found to be extremely difficult to mill the road surface closely about the periphery of a manhole cover or the like.